The present specification relates to writing track information on an optical disk for a track identification process.
An optical disk has circumferentially-arranged, spiral tracks that comprise data storage tracks. In certain optical disks, each track is divided into portions called xe2x80x9cwedges.xe2x80x9d Each wedge has a track and wedge identification information written at the beginning of the wedge. The wedge identification information on a disk surface is read by the reflected beam from the disk.
The wedge identification information may include embossed signals indicating track alignment and track seeking information. Clock synchronization signals are often recorded at the start of the wedge to synchronize a decoding clock circuit and to facilitate decoding of the track identification information during track seeking and track following modes.
However, such a system may require additional timing circuitry necessary for synchronization during track seeking and additional clock track necessary for writing the track identification information. In addition, the signal read back from embossed pits varies with head fly-height. The embossed pits are subject to debris and contamination collecting in the pits, which result in poor read back reliability.
The present disclosure involves writing wedge data, which are spatially aligned along the radial direction, using a wedge data writer. The wedge data can include track identification information. When at least one radial groove or pit molded into an optical disk is detected, the wedge data writer writes the wedge data in an area immediately following the radial pit. The wedge data written using the above-mentioned process may simplify track identification process, such as during a track seek.
In one aspect, the wedge data writer includes a pit detector, a coil driver, and a wedge data generator. In one embodiment, the writer also includes a beam coupling element, such as an optical lens system, which is configured to illuminate an optical disk with light. The pit detector receives reflected light from the optical disk and is capable of detecting the radial pit at the beginning of the wedge. The pit detector generates a trigger signal once the radial pit is detected. The coil driver receives the wedge data and energizes an electromagnetic coil to write the wedge data on the disk surface. The wedge data generator generates and sends laser pulses to the beam coupling element and the wedge data to the coil driver when the trigger signal is enabled by the pit detector. The beam coupling element and the electromagnetic coil are synchronized by the wedge data writer.
In some embodiments, the writer also includes a processor or state-machine configured to update the wedge data stored in the wedge data generator after the wedge data are sent to the optical lens system and the coil driver to be written.
In another aspect, a method for writing wedge data is disclosed. The method includes illuminating a beam of light onto an optical disk, receiving the reflected beam of light, generating a trigger signal when the reflected beam of light indicates the presence of a radial pit, outputting the wedge data for writing when the trigger signal is enabled, and writing the wedge data on the optical disk.
In another aspect, a computer-implemented process for use in writing wedge data on an optical disk is disclosed. The disk has a beginning track and an ending track where the tracking information in the wedge data is spatially aligned along the radial direction. The process includes commanding a beam writer to move to the beginning track and to follow grooves along the track, detecting radial pits molded into the optical disk, generating a trigger signal, and writing the wedge data when the trigger signal is enabled. The process also includes determining if the ending track has been reached, and exiting if it has been reached; and updating the wedge data for the next wedge if not.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other embodiments and advantages will become apparent from the